Original video: https://youtu.be/LfC2EnkV2Co
Delivered on: 15 May 2024
This video demonstrates the protocol for using the LI-6800 Portable Photosynthesis System to measure chlorophyll fluorescence and calculate quenching coefficients in Arabidopsis plants. 🌿 We'll walk you through the necessary settings, leaf selection, and measurement procedures.
What you'll learn:
Dark Adaptation: Understand the importance of dark adaptation for chlorophyll fluorescence measurements.
LI-6800 Configuration: Learn how to configure the LI-6800 fluorometer, including setting the control mode, measuring beams, flash parameters, and dark pulse settings.
Leaf Selection: We'll discuss the criteria for selecting appropriate leaves for measurement, considering factors like plant age, leaf position, and morphology.
Clamping and Measurement: See how to properly clamp the leaf in the LI-6800 chamber and take dark-adapted and light-adapted measurements.
Data Acquisition: Learn how to acquire fluorescence data, including Fv/Fm (maximum quantum efficiency of PSII) and other fluorescence parameters.
Three useful fluorescence parameters will be explored in this experiment. Fv'/Fm' represents the efficiency of energy harvesting by oxidized (open) PSII reaction centers in the leaf. Two competing processes that quench (decrease) the level of chlorophyll fluorescence in the leaf are referred to as photochemical (qP) and nonphotochemical (qN) quenching.
Many disciplines use these parameters, but the latter two are particularly useful as quantifiers in stress physiology research. All three of these parameters require Foʹ, the minimal fluorescence (in the dark) of a light-adapted leaf. How can this be determined? One method would be to allow the sample to dark-adapt and wait until all PSII centers oxidize (usually 20 minutes or more). A more expedient method would be to use far-red light to preferentially excite PSI and force electrons to drain from PSII. Only a few seconds of far-red time are needed for this to occur. The fluorometer provides a “dark pulse” routine which uses this second method to determine Foʹ.
Video Timestamps:
00:00 Introduction
02:45 Setting the machine
04:45 Creating log file
06:20 Clamp the leaf
08:00 Dark Adapted measurement
09:20 Light Adapted and Dark Pulse Measurement
Keywords: LI-6800, chlorophyll fluorescence, quenching coefficients, Fv/Fm, NPQ, photosynthesis, plant physiology, Arabidopsis, dark adaptation, fluorometer, light response.
Attribution 4.0 International — CC BY 4.0 - Creative Commons
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